Air Plan Approval; Indiana and Ohio; Infrastructure SIP Requirements for the 2010 NO2

The Environmental Protection Agency (EPA) is taking final action to approve elements of state implementation plan (SIP) submissions by Indiana regarding the infrastructure requirements of section 110 of the Clean Air Act (CAA) for the 2010 nitrogen dioxide (NO 2 ) and sulfur dioxide (SO 2 ) national ambient air quality standards (NAAQS), and by Ohio regarding the infrastructure requirements of section 110 of the CAA for the 2010 SO 2  NAAQS. The infrastructure requirements are designed to ensure that the structural components of each state's air quality management program are adequate to meet the requirements of the CAA. The proposed rulemaking for Ohio's 2010 SO 2  infrastructure submittal associated with today's final action was published on July 25, 2014, and EPA received one comment letter during the comment period, which ended on August 25, 2015. In the July 25, 2014 rulemaking, EPA also proposed approval for Ohio's 2008 lead, 2008 ozone, and 2010 NO 2  infrastructure submittals. Those approvals have been finalized in separate rulemakings. The proposed rulemaking for Indiana's 2010 NO 2  and SO 2  infrastructure submittals associated with today's final action was published on February 27, 2015, and EPA received one comment letter during the comment period, which ended on March 30, 2015. The concerns raised in these letters, as well as EPA's responses, are addressed in this final action.